The present invention relates generally to irrigation tape and more specifically to drip irrigation tape having indicia and methods of manufacturing irrigation tape having indicia.
Drip irrigation systems are commonly used in agriculture and horticulture to conserve water and reduce costs. A drip irrigation system includes lengths of plastic tubing or tape placed near the roots of plants, either above the ground or embedded in the earth. Drip irrigation tape has numerous small outlets supplying drops of water continuously to the plants. As well as conserving water, the systems provide a uniform water supply to plants which improves crops and reduces salt accumulation and fertilizer loss in the soil.
Drip irrigation tape is commonly fabricated from a thin pliable plastic strip folded lengthwise. The two edges of the tape are overlapped and joined together to form a flat hollow tape. Under pressure, the tape opens out into a generally cylindrical form to provide a main conduit for irrigation water flowing to the irrigation areas. The drip irrigation tape also includes a much smaller secondary conduit, usually located along the seam formed by the overlapping edges of the plastic strip. The smaller conduit is connected to the main conduit to form a narrower passageway for the water flow, reducing the rate that water is released into the soil.
Typically, the drip irrigation tape must be installed in a particular orientation. In most systems, the performance of the drip irrigation system is optimal when the drip irrigation tape is installed with the smaller conduit oriented at the top of the tape, facing up. As a result, irrigation tape may have markings on the tape indicating the proper orientation. For example, one side of the tape may be marked with the words xe2x80x9cTHIS SIDE UPxe2x80x9d.
Further, manufacturers of irrigation tape often include markings identifying the manufacturer to indicate the source of the product for advertising purposes or to direct the installer or user of the tape to the appropriate manufacturer for assistance or information.
One known method of marking drip irrigation tape includes printing lettering or other markings directly on the surface after the irrigation tape has been formed. This method, however, has several manufacturing and performance disadvantages.
The marking of irrigation tape using printing techniques requires additional manufacturing equipment that must be maintained. Separate ink printing equipment must be added to the production line to perform the printing process. The additional equipment may require repairs and continuing maintenance such as lubrication and cleaning. Accordingly, the cost of the manufacturing process is increased due to the cost of the equipment, maintenance of the equipment, and additional space required for the extra equipment in the production facility.
Production costs are also increased by the cost of the additional materials required for printing such as ink and cleaning solutions for cleaning the tape prior to the printing process.
Product quality and costs are also affected by indirect manufacturing process issues such as a slowed manufacturing process due to the additional marking process and potential delays in production due to malfunctions and maintenance of the printing equipment. The additional equipment presents additional components that may malfunction resulting in the shutdown of a production line. Maintenance such as ink replacement or lubrication of the additional equipment may result in delays in production.
The required drying time of the ink markings results in delays in the drip irrigation tape packaging process. For example, the drip irrigation tape cannot be wound on a spool until the ink is dry. In addition to the additional drying time, the ink drying process may require additional floor space for drying the irrigation tape within the production facility.
Further, the final ink marked tape is not reliable since ink markings may become hard to read after being submerged in the soil. Chemicals in the soil, temperature changes, and other environmental factors may dull or eliminate the ink markings on the irrigation tape. The ink markings are also susceptible to distortion from abrasions during packaging, installation and use.
Therefore, there exists a need for a drip irrigation tape with indicia that are reliable and are manufactured using an efficient and reliable method that does not increase the production time and reduces the need for additional equipment.
In an exemplary embodiment of the invention, a strip of semi-molten material is extruded and shaped by deforming the surface of the strip of semi-molten material to form indicia on its surface. While deformed, the strip of semi-molten material is cooled to form a strip of flexible material having indicia. The flexible strip is folded lengthwise and sealed to form the drip irrigation tape with the indicia on an outer surface.
Indicia forming features on a cylindrical surface of a shaping drum form deformations in the surface of the strip of semi-molten material as a compression drum forces the strip of semi-molten material against the shaping drum. In addition to the indicia forming features on the surface of the shaping drum, the shaping drum may also have contours such as grooves that form functional features within the drip irrigation tape. Alternatively, a secondary process may be employed to form a secondary flow channel within the tape, or a component having a pre-formed secondary conduit may be fixed to the tape. Thus, the indicia may be formed first around a first shaping drum, and the strip may then be guided to a secondary process where the secondary flow channel is formed, or vice versa.